Moving bin sheet collators or sorters for use with office copiers and printers have evolved in which a set of receiver trays are supported for movement relative to a sheet entry location, at which sheets enter the sorter from a copier or printer, so that the trays are close together at positions above and below the sheet entry location but are widely spaced apart at the sheet entry location to facilitate entry of the sheets into a bin.
Examples of such sorters are illustrated in the prior patents of Lawrence, U.S. Pat. No. 4,343,463 granted Aug. 10, 1982; DuBois and Hamma, U.S. Pat. No. 4,328,963 granted May 11, 1982; and DuBois, U.S. Pat. No. 4,478,406 granted Oct. 23, 1984, as well as in Hamma application Ser. No. 06,483,596, filed Apr. 11, 1983, owned commonly herewith.
Such sorters utilize cams to engage cam follower portions of the trays to move the ends of the tray adjacent to the sheet entry location between the closely spaced positions above and below the cams which define the enlarged space between the trays at the sheet entry location. The cams are driven in opposite directions by a drive motor under control of suitable means to cause operation of the motor as required to collate a desired number of sets of sheets having a desired number of sheets per set. The motor control means may be self-contained in the sorter or the control means may be incorporated, as well, in the host copier.
In any event the motor is caused to be driven in opposite directions and intermittently depending upon the sorting task to be performed, so that the sorting is bi-directional, i.e., the trays move up and down during sorting operations to receive sheets supplied from the copier or printer.
Each revolution, or partial revolution, of the cams, depending on the profile of the cam and the motor controlling means, causes the cams to move from a stationary dwell position to an active position to move the trays. Activation of the cams, in many forms, will inherently cause initial impact with the cam followers before the followers commence to move the trays. This impact causes objectionable noise which is increased when the cam follower portions of the trays are spring biased in one direction into contact with the cams to cause the cams to engage the follower portions of the trays and/or when the cam must move at a high rate of speed.
In the case where the cam follower portions of the trays directly abut when the trays are in their closely spaced positions above and below the cams, the noise problem can be alleviated, to some extent by segregating the follower portion and the tray spacing portions of the tray, particularly in the case of utilization of certain cam forms like the helical form of Lawrence U.S. Pat. No. 4,343,463 or DuBois U.S. Pat. No. 4,478,406.
However, in the case of cam wheels of the type referred to in DuBois and Hamma U.S. Pat. No. 4,328,963 and the Hamma application Ser. No. 483,596, as "Geneva" wheels having one or more radial openings formed in the periphery of a rotary mechanism, the noise problem is severe, in part due to the fact that such sorters typically employ a spring to load the trays located below the cams upwardly for engagement with the cams.
The magnitude of the noise is a function of a) the speed of travel of the cam when the follower on the tray engages in the radial notch or is disengaged from the notch by engagement with a wall defining a guide slot for the follower and b) the load on the follower caused by springs and/or the weight of the trays, including paper therein. Accordingly the problem is exacerbated in the higher speed sorters in which the cams must be rapidly moved to shift the trays during a relatively short period of time between copies.